<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="js/vue.js"></script>
</head>
<body>
    <div id="app">
        <div :class="cnameObj">这是div</div>
        <button @click="handleAdd">添加class</button>
    </div>
    <script>
        const vm = new Vue({
            el:"#app",
            data:{
                cnameObj:{
                    on:true,
                    active:true,
                    aa:true
                }
            },
            methods: {
                handleAdd(){
                    // 不饿能直接在对象下添加属性，因为没有被Object中的get，set拦截
                    // this.cnameObj.dd = true
                    this.$set(this.cnameObj,"cc",true)
                    Vue.set(vm.cnameObj,"dd",true)
                }
            },
        })
        //动态添加class属性
        // Vue.set(vm.cnameObj,"dd",true)
    </script>
</body>
</html>